DC Sports STH4301B Subaru Impreza WRX/STI Polished Stainless Steel Turbo Manifold Perfect upgrade to extract the most power from the factory turbocharged vehicle Special manufacturing techniques to virtually eliminate the chance of failure from high temperature Plasma cut materials for welding, using a slower weld process and thicker rod for deeper weld penetrations Purging the inner tube sections with argon gas to strengthen the backside of the welds